INORGANIC CHEMISTRY A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site iodine (I) Iodine. Credit: RTC & Wikipedia A lustrous, dark gray to purplish-black, corrosive, poisonous element that is a member of the halogen family. It gives rise to a violet vapor (I2 molecules). Simple solutions (e.g. in carbon tetrachloride, CCl4) are violet; solutions in which there is an appreciable charge transfer (e.g. C2H5OH, KI/H2O) are brown. Iodines reacts with other halogens (to give inter-halogen compounds), and bases (to give iodates). Several of its isotopes are radioactive, including I-131, which is used as a tracer and in thyroid disease diagnosis and therapy. Its compounds are used as germicides, antiseptics, and dyes. atomic number 53 relative atomic mass 126.904 electron configuration 1s22s22p63s23p64s23d104p65s24d104p5 first ionization energy 1,008 kJ/mol electronegativity 2.7 atomic radius 133 pm ionic radius 216 pm melting point 113.5 °C (236.3 °F) boiling point 184.4 °C (363.8 °F) relative density 4.93 (solid, 20 °C) Iodine and health Iodine is essential for the formation of the thyroid hormones, triiodothyronine (T3) and thyroxine (T4). These hormones control the rate of metabolism and growth and development. About 100 to 300 micrograms are needed daily. A dietary shortage of iodine may lead to goiter (enlargement of the thyroid gland) or to hypothyroidism (underactivity of the thyroid gland). Iodine deficiency in the newborn can lead to cretinism. The amount of iodine in food depends on the amount contained in animal feed and the amount in the soil; shortages occur in limestone areas. Shortages can be overcome by consuming bread or table salt fortified with iodine or iodate. Medical uses of iodine Iodine is sometimes given to people who have consumed food or drink contaminated with radioactive iodine. In such cases, absorption of the body of nonradioactive iodine reduces the absorption of the radioactive iodine. Radioactive iodine is sometimes used to damage, and thus to reduce the activity of the thyroid gland in cases of thyrotoxicosis (a toxic condition resulting from overactivity of the thyroid gland). Iodine compounds are used as antiseptics, in radiopaque contrast media used in some X-ray procedures and in some cough remedies. Related category    • INORGANIC CHEMISTRY Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP